Field of the Disclosure
The present invention relates generally to imaging. More specifically, examples of the present invention are related to complementary metal oxide semiconductor based image sensors.
Background
Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors, and in particular, complementary metal-oxide-semiconductor (CMOS) image sensors (CIS), has continued to advance at a great pace. For example, the demands for higher resolution and lower power consumption have encouraged the further miniaturization and integration of these image sensors.
Two fields of applications in which size and image quality are particularly important are security and automotive applications. For these applications the image sensor chip must typically provide a high quality image in the visible light spectrum as well as have improved sensitivity in the infrared and near infrared portions of the light spectrum. For instance, infrared or near infrared image sensors may be used to provide improved visibility and imaging in low light and foggy conditions as well as help detect warmer objects in cooler environments.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.